Download failed: HTTP/1.1 404 Not Found
My girlfriend had the same problem yesterday (we share a connection, FWIW).
When I went to the download link on the home page I was able to download the release with no problem, as well as the latest beta (which, oddly, is older than the release - you may want that link to point to the release as well). I continue to not be able to auto update, and I'm about to just install it directly (so won't test it any more).
I'm running on Win XP SP2, updating from 1.8.587.
 Once updated, it works just fine, as normal. As always, many thanks for providing such a great tool.